Contemporary cellular phone systems and broadband wireless metropolitan networks 20, as shown in FIG. 1, are generally divided into a number of cells 22 distributed in a pattern to preclude co-channel interferences and provide coverage of mobile and fixed subscriber units operating within the service area of the system. Each cell 22 includes a base station 24 that employs radio frequency (RF) transceiver equipment, antennas 26, and wire line 28 communication equipment. Mobile/fixed subscriber units 30 within the geographic area of the cell site use RF transceiver equipment to communicate with RF transceivers within the base station 24. The base station 24 relays voice and data traffic to/from the subscriber mobile units or devices (e.g. a phone) 30 and to/from a Mobile Telephone Switching Office 32 or Access Service Gateway which in turn are connected to a central network such as the public switched telephone network (PSTN) 34 or packet switched networks such as the Internet, for example.
To improve the capacity of a base station 24 to handle more mobile users 30, cells 22 may be divided into sectors 38 or are further subdivided into smaller cells with the base station 24 being replaced with lower cost, reduced capability micro or pico cells 36. In some configurations, distributed antenna systems (DAS) may be employed to optimize the RF distribution in larger cells in order to increase capacity at an even lower cost than with pico and/or micro cells 36. These approaches permit the reuse of a limited number of expensive RF channels without incurring the costs of one or more complete base stations 24. Further, these techniques may also be used to extend coverage to areas within the cell site where RF propagation may be limited by obstruction, such as in buildings and tunnels, or to areas where the amount of traffic (revenue) does not justify the investment required for a complete base station 24. Distributed antenna systems allow the RF coverage to be adapted to the specific environment in a homogeneous way to assist in reducing the amount of introduced interference. In addition, the amount of extra traffic is kept low as only existing cells are distributed and no hand-off between cells is required.
In order to reduce the costs associated with the development of their communication systems, multiple service providers often locate their base stations 24 at the same geographical point. The providers can then share such items as antennas, antenna towers, primary power drops, land costs, and regulatory costs. These service providers may employ multiple RF bands, multiple channels within the same RF band and multiple air interface standards (e.g. CDMA, UMTS, TDMA, and WiMax). The cost for each service provider to extend coverage to increase capacity by deploying their own micro/pico cells and/or distributed antennas may be quite high. Further in some areas where RF propagation is poor, such as sporting venues or shopping malls, the owners of such facilities may not permit the installation of such equipment by multiple service providers for aesthetic reasons or because of space limitations.
Therefore, there is a need in the art for a system that maybe used by multiple service providers to extend coverage and increase capacity.